The Host Defense Group of the Laboratory of Respiratory Biology, Division of Intramural Research, National Institute of Environmental Health Sciences, headed by Michael B. Fessler, MD now enters its 13th year at the NIEHS. Publications since the last annual report include: 1. a collaborative report that CD4 (a T cell gene)-driven expression of the cancer gene K-ras causes an atypical proliferative pneumonitis 2. a collaborative report of the effects of the drug simvastatin on the proteins that bind to the immune receptor TLR2. 3. a collaborative report that the cholesterol transporter ABCG1 suppresses changes in the lung that mimic the disease sarcoidosis 4. a book chapter about research modeling of influenza pneumonia 5. a senior-author paper identifying the protein Lrch4 as a novel receptor that controls inflammation. 6. an editorial on drugs that target the neutrophil in COPD 7. a senior author publication showing that variants of the gene IRGM associate with risk for Crohn's disease 8. a senior author report identifying the lipid cholestenoic acid as a biomarker in acute respiratory distress syndrome. Additional accomplishments since our last report include filing of a patent application by Dr. Fessler on a potential novel strategy for intervening on lung inflammation (No. 62/664,805 (4/30/18)), receipt by Dr. Fessler of a 'Top Reviewer Award' by American Journal of Respiratory Cell and Molecular Biology, appointment of Dr. Fessler as an Associate Editor by the same journal, appointment of Dr. Fessler as a member of the External Advisory Committee of the LSU COBRE program, and presentation of findings from Dr. Fessler's group, in the form of oral presentations and posters, at several national/international meetings.